1. Field of the Invention
The invention relates to an automatic valve assembly for connecting to an exhaust duct of a clothes dryer so that the dryer can be used also as a humidifier and heater.
2. Prior Art
Domestic clothes dryers in which clothes to be dried are exposed to hot air from a heater have been known for many years. During operation of the dryer, a relatively large volume flow of moist air at a moderately high temperature and relative humidity is exhausted from the dryer to outside the building. It is known that such dryers require relatively large amounts of heat energy and, after the drying, most of this energy is lost to atmosphere.
Humidifiers have also been known for many years, and are particularly useful in winter in buildings situated in dry areas remote from large bodies of water. During winter, low ambient temperature reduces absolute moisture content of outside air and when the outside air is drawn into the house and heated to normal temperature it attains a very low relative humidity. Thus, particularly during the winter when additional space heating is required, humidifiers are used and these also require relatively large amounts of energy.
It is known to recover the hot moist air from a clothes dryer by diverting the exhaust from the dryer into the building. This increases relative humidity and temperature of the air in the building and, to prevent lint from the clothes from passing into the building, it is usual to pass the dryer exhaust through a filter. Thus by a simple conversion the dryer can be used also as a heater humidifier during its normal drying cycle. However, the filters can quickly become clogged with lint which restricts exhaust flow from the dryer, reducing drying efficiency and commonly raising dryer temperature which can trigger an "over-heat" switch of the dryer which switches off the dryer. Occasionally lint in a dryer burns if the "over-heat" switch is not triggered, and this danger may be increased if the clogged filter is not cleaned or replaced. It may be for this reason that heater/humidifier converters using filtered exhausts from clothes dryers to increase household temperature and humidity have been relatively unpopular.